Torque split gearbox for rotary wing aircraft
A gearbox system for a dual coaxial counter rotating rotor assembly includes an input shaft to input a first torque into the gearbox system and a transfer shaft operably connected to the input shaft to transfer the first torque therethrough. Two gear sets are operably connected to the transfer shaft. Each gear set includes a first output gear to transfer a second torque acting in a first direction to a first rotor of a rotor assembly and a second output gear to transfer the second torque acting in a second direction opposite the first direction to a second rotor of the rotor assembly. The second torque transferred by each gear set of the two gear sets is substantially equal.
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This is a continuation application that claims the benefit of priority to U.S. patent application Ser. No. 14/017,674, which was filed on Sep. 4, 2013. The entire contents of U.S. patent application Ser. No. 14/017,674 are incorporated herein by reference.
BACKGROUNDThe subject matter disclosed herein relates to the art of rotary wing aircraft and, more specifically, to gearbox systems for rotary wing aircraft.
A gearbox system of a rotary wing aircraft transfers power from an engine, or multiple engines, for example, a turbine engine, to the rotor system. A typical system directs power from the engine to a single rotor system including a plurality of rotor blades. Since rotational velocity of the rotor is typically lower than the rotational velocity of the engine, the gearbox is used to reduce the rotational velocity of the turbine engine. Torque is subsequently increased through a series of intermediate gear stages and shafts, with an output velocity provided to the rotor system.
In other rotary wing aircraft with more complex rotor systems, the complexity of the gearbox typically also increases. For example, some rotary wing aircraft, such as the X2® helicopter produced by Sikorsky Aircraft Corporation, have two coaxial counter rotating main rotor assemblies. As such, the gearbox must be configured to transfer engine power to both rotor assemblies at the required directions of rotation, requiring two large final reduction stages. Further in X2®-type aircraft, the gearbox is further utilized to transfer power to a propeller assembly, typically located at a tail of the aircraft, to provide additional forward thrust. Consequently, the typical gearbox for such an aircraft is large and heavy.
BRIEF DESCRIPTIONIn one embodiment, a gearbox system is connectable to an exterior shaft which relays a first torque with respect to the gearbox. The gearbox system includes an input bevel shaft operably connectable to the exterior shaft to transfer the first torque therethrough and two gear sets operably connected to the input bevel shaft. Each gear set includes a first output pinion to transfer a second torque acting in a first direction to a first gear and a second output pinion to transfer the second torque acting in a second direction opposite the first direction to a second output pinion coaxial with the first output pinion. The second torque transferred by each gear set of the two gear sets is substantially equal.
In another embodiment, a drive system for a dual coaxial counter rotating assembly includes an engine outputting a first torque via an input shaft and a gearbox assembly to reduce the first torque to a second torque and transfer the second torque to the dual coaxial counter rotating assembly. The gearbox assembly includes an input bevel shaft operably connected to the input shaft to transfer the first torque therethrough and two gear sets operably connected to the input bevel shaft. Each gear set includes a first output pinion to transfer a second torque acting in a first direction to a first rotating element of the dual coaxial counter rotating assembly and a second output pinion to transfer the second torque acting in a second direction opposite the first direction to a second rotating element of the dual coaxial counter rotating assembly. The second torque transferred by each gear set of the two gear sets is substantially equal.
In yet another embodiment, a rotary wing aircraft includes an airframe and a rotor assembly. The rotor assembly includes a first rotor rotatable about a rotor axis in a first direction and a second rotor coaxial with the first rotor and rotatable about the rotor axis in a second direction opposite the first direction. A drive system includes an engine outputting a first torque and a gearbox assembly to reduce the first torque to a second torque and transfer the second torque to the rotor assembly. The gearbox assembly includes an input shaft to input the first torque into the gearbox assembly, an input bevel shaft operably connected to the input shaft to transfer the first torque therethrough and two gear sets operably connected to the transfer shaft. Each gear set includes a first output pinion to transfer a second torque acting in the first direction to the first rotor and a second output pinion to transfer the second torque acting in the second direction to the second rotor.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
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While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. For instance, aspects can be used with propeller assemblies, turbines, and/or fans where blade pitch control and compactness of design may be useful. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. A rotary wing aircraft, comprising:
- an airframe;
- a rotor assembly including a first rotor rotatable about a rotor axis in a first direction and a second rotor coaxial with the first rotor and rotatable about the rotor axis in a second direction opposite the first direction; and
- a drive system including plural engines outputting torque and a gearbox assembly to reduce torque produced from one or more of the engines to a reduced torque and to transfer the reduced torque to the rotor assembly, the gearbox assembly comprising:
- an input shaft to input the torque into the gearbox assembly;
- an input bevel shaft operably connected to the input shaft to transfer the torque therethrough; and
- two gear sets operably connected to the input bevel shaft, each gear set including first and second intermediate shafts,
- the first intermediate shaft having a first intermediate idler meshed with a transfer gear of the input bevel shaft and a first output pinion to transfer the reduced torque to the first rotor, and
- the second intermediate shaft having a first intermediate gear meshed with the first intermediate idler and a second output pinion to transfer the reduced torque to the second rotor.
2. The rotary wing aircraft according to claim 1, wherein the first output pinion and the second output pinion have axes of revolution parallel to an input bevel shaft axis.
3. The rotary wing aircraft according to claim 1, wherein the rotor assembly further comprises:
- a first bull gear operably connected to the first rotor via a first rotor shaft; and
- a second bull gear operably connected to the second rotor via a second rotor shaft coaxial with the first rotor shaft.
4. The rotary wing aircraft according to claim 3, wherein the first output pinion is meshed with the first bull gear and the second output pinion is meshed with the second bull gear.
5. The rotary wing aircraft according to claim 3, wherein the second rotor shaft is located inside of the first rotor shaft.
6. The rotary wing aircraft according to claim 1, further comprising a propeller assembly including:
- a propeller output gear operably connected to the input bevel shaft to drive a propeller output shaft; and
- a propeller operably connected to the propeller output shaft to provide translational thrust for the aircraft.
7. A rotary wing aircraft, comprising:
- first and second coaxial, counter-rotating rotors;
- one or more engines disposed to produce torque to drive respective rotations of the first and second coaxial, counter-rotating rotors; and
- a gearbox assembly configured to reduce the torque produced by the one or more engines and to transfer the reduced torque to the first and second coaxial, counter-rotating rotors,
- the gearbox assembly comprising:
- an input shaft;
- an input bevel shaft operably connected to the input shaft to transfer torque input by the input shaft therethrough; and
- two gear sets operably connected to the input bevel shaft, each gear set including first and second intermediate shafts,
- the first intermediate shaft having a first intermediate idler meshed with a transfer gear of the input bevel shaft and a first output pinion to transfer the reduced torque, which is reduced from the torque input by the input shaft, to the first rotor, and
- the second intermediate shaft having a first intermediate gear meshed with the first intermediate idler and a second output pinion to transfer the reduced torque to the second rotor.
8. The rotary wing aircraft according to claim 7, wherein the first output pinion and the second output pinion have axes of revolution parallel to an input bevel shaft axis.
9. The rotary wing aircraft according to claim 7, further comprising a propeller assembly including:
- a propeller output gear operably connected to the input bevel shaft to drive a propeller output shaft; and
- a propeller operably connected to the propeller output shaft to generate translational thrust.
10. The rotary wing aircraft according to claim 7, further comprising an intermediate gear set for association with at least one of the one or more engines, the intermediate gear set being configured for additional torque splitting.
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Type: Grant
Filed: Jan 29, 2016
Date of Patent: May 2, 2017
Patent Publication Number: 20160152342
Assignee: SIKORSKY AIRCRAFT CORPORATION (Stratford, CT)
Inventor: Todd A. Garcia (Mansfield, TX)
Primary Examiner: Joseph W Sanderson
Assistant Examiner: Christopher Hutchens
Application Number: 15/010,187
International Classification: B64D 35/06 (20060101); F16H 37/06 (20060101); B64C 27/12 (20060101); B64C 27/10 (20060101);